Method of making tubular bearings



May 1, 1945. c. HARDY l 223714,747

METHOD MAKING TUBULAR. BEARINGS v Filed March '9, 1 942 3 Sheets-Sheet 1 ATTORNEYS iled March 9, i942 3 Sheets-Sheet 2 K Zecss y INVENTOR (Zar/@s Hardy ATTORNEYS Filled March 9, 1942 l c. HARb-Y 2,374,747 Y METHOD OF MAKNG TUBULAR BEARINGS 3 Sheets-Sheet 5 y INVENTOR (Zar/cv' //WQQ/ ATTORNEYS Patented May yl, 1945 OFFICE METHOD F' MAKING TUBULAR BEARINGS charles nii-ay, Pelham Manor, N. Y., mmm to' Hardy Metallurgical Company, New York, N. Y., a corporation of Delaware Application March vil, 194.2, Serial No. 433,900

' z claims. (ci. zsuas) 'I'his invention is concerned with the formation of metal linings in tubes and contemplates improvements in processes therefor. More particularly, the invention is concerned with,the production from metal powder of annular linings in tubular bearings and the like.

Bearings comprising a tubular housing of relatively inexpensive and plentiful metal such as steel or iron and a' thin annular lining of special( bearing metal such as babbitt or bronze possess numerous advantages, not the least of which resides in the fact that they permit a great saving in strategic materials such as tin. However, it has not been practical heretofore to form thin annular linings in tubular bearings by powder metallurgy. I have developeda simple and practicable method lwhereby this may be accomplished and which assures that the metal powder will be adequately compacted against the tubular hous- 'ing in which the lining` is formed.

In accordance with my invention, a metal lining is formed on the inside of a tube by placing a layer of metal powder on the inside wall thereof and compacting the layer against thewall by lsqueezing a plastic core outwardly against the layer, the term plastic being employed to de- ,scribe liquids and semi-solids such as water, oil,

jelly, rubber, etc. Preferably the core is made of a resilient material such as rubber, and the squeezing action is brought Aabout by compressing the core longitudinally of the tube, i. e., in the direction of the tubes axis.

'I'he layer of metal powder may be placed on the inside of the `tube in any convenient manner.

Thus, the layer may be formed by pouring the metal powder into the annular space between the tube wall and a concentrically disposed core which ,has a cross-section less than that of the inside of the tube. The layenmayalso beformed by placing a loose mass of metal powder (with or y without a binder) within the tube and spinning the tube on its axis so that thep'owder'is forced Y against the tube wall by a centrifugal force sufnc'ient inl magnitudeto cause the powderto adhere. g.

These and other features of my invention will be more thoroughly understood in the light of the following detailed description taken in conjunction with the accompanying drawings. in which: Fig. 1 is a fragmentary vertical section taken through ii press equipped with a rubber core and adapted to the practice of my invention;v

Fig. 2 is a fragmentary vertical section taken through another type 0f equipment adapted to` tbe'practice of myA invention and provided with a hollow rubber core into which water or other iluidmay be pumped; and

Fig. 3 is a fragmentary vertical section through still another type of apparatus for the practice of my invention' and in which the core is entirely liquid.

. Referring now to Fig. 1, it will be observed that the apparatus comprises a die I0 having avertical bore into which a, tubular bearing housing Il to be lined is tted snugly. A bottom punch I2 provided with an upwardly projecting guide pin i3 is disposed concentrically in the bore of the die. An annular rubber core I4 is disposed around the guide pin and extends within a short distance of the inside wall of the tubular bearing housing,

. so that there is left an annular space or powder sponds in cross-section to the bottom punch and.

the rubber core, is disposed above the core and is adapted to push the rubber core downwardly against the bottom punch. A concentric bore in the top punch is adapted to receive the guide pin, so that the latter may slide therein. t

In the operation of the apparatus of Fig. 1, the rubber core, mounted on the guide pin, is disposed in the position shown in the drawings, and the top punch is raised to a position higher than that shown in thedrawings, so as to facilitate illling the annular space I5 with metal powder, for example a mixture of bronze powderwith about 2% graphite. When the space has been filled, the top punch is brought down and compresses the rubber core downwardly and at the 4 same time outwardly, since pressure tends to be transmitted in all directions in'rubber and other semi-solids and liquids. The .top and bottoms punches then are forced together until a pressure of, say, 30 tons per square inch of punch cross-section is required for further movement,

and this adequately and uniformly compacts the metal powder against the inside wall of the bearing housing to form a coherent and adherent annular layer. Thereafter, the top punch is raised and the rubber core`shrinks to its original position (that shown in the'drawlngs) leavinga substantial space between the lining and the coxe. At this point, a concentrically disposed'eiection ring Il which is -journaledabout the bottom punch is forced upwardly, so. that the bearing housing. withits adhering lining of compressed metal powder is pushedupwardly out of the die, from which l latter Iposition it may beremov'cd.

litter the uned bearing hss been removed from the die, it is subjected to a sintering operation to cause the particles of metal powder to become welded to each other and to the housing. In some instances. the sintered layer will be suiliciently uniform to serve as a bearing without any additional work. However, if desired, the bearing may be subjected to a coining operation. In such case, a punch that is somewhat larger in crosssection than that shown in Fig. 1 is forced longitudinally through the bearing to produce a smooth inside surface.

If desired, the sintered layer on the inside of the bearing may be machined on a lathe or other apparatus to bring it to requisite size and smoothness.

Referring now to Fig. 2, it will be observed that the apparatus comprises a die 2U with a vertical bore into which is tted a tubular bearing housing 2l. The apparatus is provided with an ejection punch 22 which is slidable in the bore of the die and has a recess 23 in its upper end. The apparatus is provided with an opposing or top punch 24 which is likewise slidable in the bore of the die and may be raised or lowered with respect thereto. The top punch is also provided with a concentric recess 25, the top of which is connected to a water pressureline or conduit 26 through which water maybe pumped under pressure. Within the recess of the top punch and extending below it is a hollow rubber sack or core 2l. This core is fastened iirmly into the upper recess around the water pressure line and is closed at the other end so that it forms a cylindrical sack. The cross-section of the sack in the undistended condition is slightly less than the inside bore of the tubular bearing housing.

In the operation of the apparatus of Fig. 2, a layer 28 of metal powder is disposed in the tubular bearing housing before the bearing housing is placed in the apparatus. This may be done conveniently by placing loose metal powder in appropriate amount and accompanied by a suitable binder, for example lacquer, in the housing and then spinning the housing on its axis to cause. the powder to spread over the inside surface and fill the annular groove 29. With the bearing thus lined with a coherent but substantially uncompacted layer of metal powder, it is disposed in the apparatus on the ejection punch, and the top punch is lowered so that the rubber core extends through the bore of the bearing housing. With the ejection punch and the top punch held in these positions, water or other fluid is pumped in through the water pressure line so that the rubber core is distended and squeezes the metal powder layer against the wall of the housing. The pressure within the apparatus is built up to, say, tons per square inch of inside bearing surface.

-The water pressure is then reduced, as by pumping the water out oi the apparatus. This causes the core to shrink away from the compacted lining of the housing. The top punch and the core are then withdrawn from the apparatus and the line .bearing is ejected from the die by forcing the ejection punch upwardly.

The line. bearing produced in the apparatus of Fig. 2 is subjected to a sintering operation as described in the case oi Fig. l. Thereafter, the sinteredbearing may be subjected to a coining or machining operation to improve its bearing surface, i. e., the inside of the lining.

Itwuibeobservedmatmtheppanmof' formly and thoroughLv compacted against the inside wall of the housing.

To consider the apparatus of Fig. 3, a tubular bearing housing 30 is disposed with a relatively snug rit in the vertical bore of a die 3l after the bearing housing has had applied to it a powder layer 32. The annular powder layer may be formed in the bearing housing in any convenient method, for example by the centrifugal operation 'described in the case of the apparatus of Fig. 2. In the die, the bearing housing rests on a bottom punch 33 which nts snugly in the bore oi the die, but is slidable therein. After the housing is so positioned, a top punch 34 is slid into the top of the die, where it nts snugly on the top of the bearing housing. Then liquid, for example oil or water, is pumped into the top punch through a concentric supply conduit 35. This forms a liquid core 36 inside the powder layer and forces the powder layer outwardly against the wall of the bearing housing with any desired pressure, said 30 tons per square inch.

In order to bring about a more adequate compacting of the powder in the housing, a tubular insert 31 of cardboard, thin metal, or other relatively flexible material may be placed inside the lined bearing housing before the compression step.

After the compression has been accomplished by pumping the liquid into the core, the pressure is released and the upper top punch and the bottom punch are both raised and the bearing with its compacted lining is removedrrom me apparatus and subjected to sintering and the other subsequent treatments already described.

My invention is applicable to the lining of very long tubes, although in most applications, for example bearings,the tubes will be relatively short. However, irrespective of the length of the tube, it is possible to obtain an equalization of lateral pressure so that the powder layer inside the tube is uniformly compacted in all areas.

The tube to be lined may be of any appropriate metal and may be thick or thin. In all cases the die should be sufficiently strong to backup the tube adequately.

For long tubes, the apparatus of Fig. 2 and Fig. 3 are preferable. The apparatus of Fig. 1 is particularly useful in the compression of powder layers within relatively short tubes, when it is Vnot necessary to obtain absolute equality of pressure over a long length of tube.

I claim:

1. In the formation of a metal lining on the inside wall oi.',a tube, the improvement which comprises placing a mass of discrete metal powder particles on the inside wall of the tube, forming the mass of metal powder particles into a layer, placing a plastic core in the tube inside the space occupied by the powder, and compacting the layer of powder against the interior wall of the tube by squeezing the plastic core outwardly against the wall.

2. In the formation of a metal lining on the inside wall of a tube, the improvement which comprises forming an annular layer of discrete metal powder particles on the inside wall of the tube by spinning the tube on its axis so that the powder isforced against the wall thereof, placing a plastic core in the tube inside the space occupied by the powder, and eompacting the layerofpowdernainlttheintericrwdloftbehibe btgegq'ledng the plastic core outwardly minst m HARDY. 

